Method of separating ortho- and para-phenylphenols



NOV# 8, 1932- G. H. COLEMAN METHOD OF SEPARATING ORTHO- AND PARA-PHENYLPHENOLS Filed De. 5, 1929 ISD www@

INVENTOR BY {1p/M femm Jim@ ATTORNEY Patented Nov. 8, 1932 UNrl'rDl STATES PATENT QFFIC GERALD H. COLEMAN, OF MIDLAND, MICHIGAN, .ASSIGNOR T0 THE DOW. CHEMICAL COMPANY, OFVMIDLAND, MICHIGAN, A CORPORATION MICHIGAN Murr-:toner snrnnn'rme on'rno- .AND PARA-PHENYLPHENQLS Aptiiction ied- December 5, 1929.Y Serial-Ndfinls.

The present invention relates to thel separation of phenylphenols, particularly to the separation and purification of orthoand paraphenylphenols by crystallization thereof from Y mixed organic solvents.

The present method, which is adaptable toV the separation of a mixture of phenylphenols,

or tothe purification of individual phenylphenols, is based on the fact that the phenylphenols are soluble in volatile mixed solvents e to .different degrees. For instance, when a mixture of orthoand para-phenvlphenols is dissolved in and thenv crystallized from lsuch solvents, the para compound separates out first, then a mixture of the para and ortho forms, and then substantially pure ortho compound crystallizes out. My invention, then, consists of the improved' method hereinafter fully described and particularly pointed out inthe claims, the annexed drawing and the; followingdescription setting forth in detail several modes of carrying out my invention, such disclosed modes illustrating, however, but several of various ways in which the principle of my invention may be used.

Insaid Yannexed drawing i Y Fig. 1 is a chart giving a curve which shows the relationship between percentage composition of mixtures of -orthoand para-phenylphenols to the-melting pointsthereof.` n

A. mixture of orthoand Y para-phenylphenols may be separated and purified by fractional crystallization from mixed volatile organic solvents, forexample, by'dissolving said mixture of phenylphenols ina suitable solvent in which the latter are relatively soluble, such as benzene, chlorobenzene,

which the phenylphenols, particularly theV para-compound, are relatively ,less soluble and whichis preferablymiscible with the firstV solvent, such as an aliphatic hydrocarbon,V e. g. petroleum ether, gasoline, or kerosene. The second vsolvent may be vadded hot, or the mixture may be heated after such addition to effect solution ofthe phenylphenols,in case,

roffexampie, that, the addition 'of the Second solvent has cooled4 the solutionv suficientlyto cause the formation of crystals. By vfafry'inggY thesolvents used, the proportions thereof, vand Vther-temperaturf-. of the solution, itis possible to form crystals either immediately upon adf dition of the second Vsolvent, after standing, after cooling, Yor by other treatment. Since out, first, the latter remainingin solution.V

the. para compound'is considerably lless sol- Hence the process may becontrolled so` as to form, first, crystals-` of 'para-phenylphenol,

then. a mixture of thev ortho and para forms which Vmay be returned to the process, andA l then crystals of ortho compound.

Again, when for example, crude orthophenylphenol, is purified by crystallization ,l

thereoffrom at least one ofthe fa'boveydescribed solvents, there may be vonly a small amount of thecorresponding para compoundpresent, hence the irstcrystals'to form may contain bothiorthoand para-phenylphenols,

followed bythe separation-of substantially pure ortho compound. Accordingly, the

presentmethod affords a useful means of sep'- i arating an'd/ or purifying phenylphenols.

rIhe following examples typifyl ways in which the herein described method may be operatechand show ratios of the isomeric phe- A nylphenols crystallizedlunder certain condiltions of temperatureand proportions and amountsV of solvents.v The composition or 5 purity of thelphenylphenols employed in the examples or of.v the products` obtained thereinwere ascertained by comparing the meltcurve shown in the annexed drawing.

ing pointsthereof with they meltingpoint`r Emwmplel i 100 grams of 'crudeortho-phenylphenol (M, l1?.-58to` 60.50 Cl),.c'ontaining the corresponding para compound'as an impurity, was dissolved in 50 cubic centimeters of benzene. They solution was diluted with 250'k vcubic centimeters of petroleum ether and ral'-l lowed tofstand over night at room temperlature, whereupon 38 grams of crystals (M. P.

' latter crystals Was evaporated to about 20 cubic. centimeters, diluted With about 25 cubic centimeters of petroleum ether and cooled to room temperature, thus securing an additional 16 grams of ortho-phenylphenol melting at 57.5 to 58 C. Y* Y Eample 2 A mixture of'orthoand ypara-phenylphenols, having a melting point of 133 C., and containing 25 grams of each ofthe two-isomers, Was dissolved in 200 cubic centimeters of hot ethylene dichloride. l cubic centime- 80 C.) was added to the hot solution which was then cooled to room temperature byV standing.V Bysuch procedure', 22 grams of substantially pure para-phenylphenol (M. P. 166 toi-167'O C.) crystallized out. From the ltrateV of thefcrystals there'yvas obtained an additional 2 grams of the para "compound (li/LP. 166 to 166.5a C.) by adding thereto the Washings of the first crop of crystals With 10() cubic .centimeters petroleum ether.

The filtrate,-v containing cru'de ortho-phenylphenol, Was evaporated to about 25 cc. diluted with 50 cc. of petroleum`ether, and cooled over night at room temperature, thereby obtaining 12 grams of crude ortho compound' (M. P. 58.5O to 66- G.). 'Ihe filtrate from the latter, on being cooled about 109 C, more, yielded 6 grams product P. 57 to 58.5 C.) The residual liquid Was further evaporated, diluted With petroleum ether `and cooled, thereby obtainingra'n additional 7.5

grams of substantially pureortho-phenylphenol (M. P. 57 to 58O CJ. i i

c Other mixtures of solvents, such as a mixture of benzene or'other of the aforementioned equivalent compounds and petroleum ether, gasolene or kerosene, may be employed;

'y also conditions, such aslconcentration and temperature, may be variously modified dethe two. Due to its higher melting pointl pending upon the relative proportions of plienylphenols present in the crude mixture, etc.

If desired,'the procedure maybe varied from 'that given above; for instance, after separation of the crystals containing the Y higher 'melting para-compound, the solution of ortho-compound may be distilled to remove, first, the solvent and then the orthocompound,l or the` solvent may be kdistilled off, leaving the ortho-compound as a residue.,y

The herein described method is applicable -to the separation of orthoand para-phenylphenols, or to thev purification of either of andjlovver solubility in q r, ;anic solvents, the para-compound is more'readily purified by thejf usual ,methods than is the ortho-compound.V` Hence, 'the present method particu- Vlarly affords a useful means for the separainvention maybe employed instead of the one explained, change beingmade as regards the details herein disclosed, provided l the step or steps statedby-any of the follow- I ing claims or the equivalent of such be em-` l .ployed f5' i ters of petroleumether (boiling point 60l to I therefore tinctly claim as my invention ing said compounds,the step which: consists in crystallizing para-phenylphenol 4from a solution of the above mentioned phenylphenols in an adinixture of an organic solvent I selected from'the group consisting of lbenzene, chlorobenzene, cyclohexane, tetrahy- 'dronaphthalena ether, ethyl acetate, chloroform, carbon tetrachloride, ethylene dichloride,.acetic acid, and mixtures thereof, with a liquid aliphatic hydrocarbon solvent.

particularly `'point-out and disi 2. In a method of separating orthoandl i' para-phenylphenols from a mixture containingsaid compounds, the steps which consist` in crystallizing para-phenylplienol from ajw) nols in an admixture of an` organic solvent` solution of the above mentioned phenylpheselected from the vgroup consisting of benzene, chlorobenzene, cyclohexane, tetrahydronaphthalene, ether, ethyl acetate, chloroform, carbon tetrachloride, ethylene dichloride, acetic acid, and vmixtures thereof, With Va liquid aliphatic hydrocarbon solvent, and

recovering ortho-phenylphenol ,from the".

mother liquor. i c

3. In al method of separating-orthoand para-phenylphenols fromfa mixture containing said compounds, the steps which consist in dissolving the' mixture ofV phenylphenols in an organic solvent selected from the group consistingof benzene, chlorobenzene, cyclohexane, 'tetrahydronaphthalene, ether, ethyl L .iio

acetate,V chloroform, carbon tetrachloride,- 1

, ethylene dichloride, acetic acid, and'mixtures 1 thereof, .then adding tov the solution aliquid aliphatic hydrocarbon solvent,crystal lizing and separating para-phenylphenol from the resulting solution, and recoveringY ortho-phenylphenol from the mother liquor.

4. In a method of purifying ortho-phenylphenol including vthe correspondingfparai phenylphenol as an impurity,4 the step of crystallizing out Vpara-phenylphenol from a benzene solution 'of i.the crude ortho-phenylphenol admixture'vvith a liquid' aliphatichy- Vdrocarbon solvent.

5. In a, method of separating orthoand para-phenylphenols, the steps which consist of dissolving a mixture of the same in ethylene dichloride, adding thereto a liquid aliphatc hydrocarbon solvent, and fractionally crystallizing the phenylphenols therefrom.

19Sggned by me this 30 day of November, 2

GERALD H. COLEMAN.

CII 

